title: Surface properties of surfactant-free oil droplets dispersed in water studied by confocal fluorescence microscopy.
abstract: The fluorescence spectrum of dye molecules, 4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyron (DCM), dissolved in surfactant-free n-decane droplets (average diameters of approximately 300 and approximately 2000 nm) dispersed in water was measured by a confocal microscope. The fluorescence spectra for 300- and 2000-nm droplets are found to exhibit a peak at 640 and 625 nm, respectively, and the peak red shifts with a decrease in the droplet diameter (solvatochromic shift of DCM molecules). It is concluded that (1) DCM molecules are located in a polar surface region of n-decane droplets and (2) the polarity increases with decreasing the droplet diameter.
authors.affiliation: East Tokyo Laboratory, Genesis Research Institute, Inc., 717-86 Futamata, Ichikawa, Chiba 272-0001, Japan, and Cluster Research Laboratory, Toyota Technological Institute, 717-86 Futamata, Ichikawa, Chiba 272-0001, Japan.
authors.forename: Toshio
authors.initials: T
authors.lastname: Sakai
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Takeda
authors.forename: Fumitaka
authors.initials: F
authors.lastname: Mafuné
authors.forename: Tamotsu
authors.initials: T
authors.lastname: Kondow